ABSTRACT
In addition to vaccines, there is an urgent need for supplemental antiviral therapeutics to dampen the persistent COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The transmembrane protease serine 2 (TMPRSS2), which is responsible for the proteolytic processing of the SARS-CoV-2 spike protein as virus priming for cell entry, appears as a rational therapeutic target for the clearance of SARS-CoV-2 infection. Accordingly, selective inhibitors of TMPRSS2 represent potential tools for prevention and treatment of COVID-19. Here, we tested the inhibitory capacities of the human milk glycoprotein lactoferrin and its N-terminal peptide pLF1, which we identified as inhibitors of plasminogen, a serine protease homologous to TMPRSS2. In vitro proteolysis assays revealed that, unlike full-length lactoferrin, pLF1 significantly inhibited the proteolytic activity of TMPRSS2. pLF1 inhibited both the proteolytic processing of the SARS-CoV-2 spike protein and the SARS-CoV-2 infection of simian Vero cells. Because lactoferrin is a natural product and several biologically active peptides, such as the N-terminally derived lactoferricins, are produced naturally by pepsin-mediated digestion, natural or synthetic peptides from lactoferrin represent well-achievable candidates for supporting prevention and treatment of COVID-19.
ABSTRACT
BackgroundKnowledge about humoral and cellular immunogenicity and their kinetics following SARS-CoV-2 mRNA vaccinations in immunosuppressed patients is limited. MethodsAntibody and cytokine responses were assessed in 263 patients with either solid tumors (SOT, n=63), multiple myeloma (MM, n=70) or inflammatory bowel diseases (IBD, n=130) undergoing various immunosuppressive regimens and from 66 healthy controls before the first and the second, as well as four weeks and 5-6 months after the second mRNA vaccine dose with either BNT162b2 or mRNA-1273. FindingsFour weeks after the second dose, seroconversion was lower in cancer than in IBD patients and controls, with the highest non-responder rate in MM patients (17.1%). S1-specific IgG levels correlated with neutralizing antibody titers. While antibody responses correlated with cellular responses in controls and IBD patients, IFN-{gamma} and antibody responses did not in SOT and MM patients. At six months, 19.6% of patients with MM and 7.3% with SOT had become seronegative, while IBD patients and controls remained seropositive in 96.3% and 100%, respectively. Vaccinees receiving mRNA-1273 presented higher antibody levels than those vaccinated with BNT162b2. InterpretationCancer patients may launch an inadequate seroresponse in the immediate time range following vaccination and up to six months, correlating with vaccine-specific cellular responses. These findings propose antibody testing in immunosuppressed - along with cellular testing - provides guidance for administration of additional vaccine doses, or may indicate the necessity for antibody treatment. IBD patients respond well to the vaccine, but treatment such as with TNF- inhibitors may reduce persistence of immune responses. FundingThe study was sponsored and financed by the Medical University of Vienna - third party funding by the Institute of Specific Prophylaxis and Tropical Medicine. AOR. and HS acknowledge funding by the Austrian Science Fund (FWF, P 34253-B).
ABSTRACT
Twelve subjects with positive SARS-CoV-2 neutralization test (NT) titers (>1:10) identified in a seroprevalence study with 1655 working adults were followed up for one year. Here we report that 7 of these 12 individuals (58%) still had NT titers [≥]1:50, S1-specific IgG concentrations [≥]50 BAU/ml and [≥]26% ACE2 receptor binding inhibition, measured with surrogate virus NT one year after mild COVID infection. Furthermore, NT_50 titers >1:10 and S1-specific IgG levels >60 BAU/ml present at three months post-infection persisted at detectable levels for 1 year and correlated with circulating S1-specific memory B-cells. Vaccine-induced SARS-CoV2 immune responses decline at similar rates as those after infection; thus the describes threshold of 60 BAU/ml at three months post infection might also be relevant for assessment of Ab persistence after vaccination.
ABSTRACT
Despite tremendous progress in the understanding of COVID-19, mechanistic insight into immunological, disease-driving factors remains limited. We generated maVie16, a mouse-adapted SARS-CoV-2, by serial passaging of a human isolate. In silico modelling revealed how Spike mutations of maVie16 enhanced interaction with murine ACE2. MaVie16 induced profound pathology in BALB/c and C57BL/6 mice and the resulting mouse COVID-19 (mCOVID-19) replicated critical aspects of human disease, including early lymphopenia, pulmonary immune cell infiltration, pneumonia and specific adaptive immunity. Inhibition of the proinflammatory cytokines IFN{gamma} and TNF substantially reduced immunopathology. Importantly, genetic ACE2-deficiency completely prevented mCOVID-19 development. Finally, inhalation therapy with recombinant ACE2 fully protected mice from mCOVID-19, revealing a novel and efficient treatment. Thus, we here present maVie16 as a new tool to model COVID-19 for the discovery of new therapies and show that disease severity is determined by cytokine-driven immunopathology and critically dependent on ACE2 in vivo. Key pointsO_LIThe mouse-adapted SARS-CoV-2 strain maVie16 causes fatal disease in BALB/c mice and substantial inflammation, pneumonia and immunity in C57BL/6 mice C_LIO_LITNF/IFN{gamma} blockade ameliorates maVie16-induced immunopathology C_LIO_LIMaVie16 infection depends on ACE2 and soluble ACE2 inhalation can prevent disease C_LI
ABSTRACT
BackgroundIn spring 2020, at the beginning of the first pandemic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) wave in Europe, we set up an assay system for large-scale testing of virus-specific and protective antibodies including their longevity. MethodsWe analysed the sera of 1655 adult employees for SARS-CoV-2-specific antibodies using the S1 subunit of the spike protein of SARS-CoV-2. Sera containing S1-reactive antibodies were further evaluated for receptor-binding domain (RBD)- and nucleocapsid protein (NCP)-specific antibodies in relation to the neutralisation test (NT) results at 0, three and six months. FindingsWe found immunoglobulin G (IgG) and/or IgA antibodies reactive to the S1 protein in 10.15% (n=168) of the participants. In total, 0.97% (n=16) were positive for S1-IgG, 0.91% (n=15) were S1-IgG-borderline and 8.28% (n=137) exhibited only S1-IgA antibodies. Next, we evaluated the 168 S1-reactive sera for RBD- and NCP specificity: 8.33% (n=14) had detectable RBD-specific and 6.55% (n=11) NCP-specific antibodies. The latter correlated with NTs (kappa coefficient = 0.8660) but started to decline already after 3 months. RBD-specific antibodies correlated best with the NT (kappa = 0.9448) and only these antibodies were stable for up to six months. All participants with virus-neutralising antibodies reported symptoms, of which, anosmia and/or dysgeusia correlated best with the detection of virus-neutralising antibodies. InterpretationRBD-specific antibodies were most reliably detected post infection, independent of the number/severity of symptoms, and correlated best with protective neutralising antibodies at least for six months. They thus qualify best for large-scale seroepidemiological evaluation of both seroprevalence and seroprotection. FundingThis study received funding from the Austrian Ministry of Education, Science and Research within the research framework in relation to the coronavirus disease 2019 pandemic (GZ 2020 0225 104). Key pointsPersistence of SARS-CoV-2 antibodies depends on their specificity. Total RBD-specific antibodies are those that are stable for up to at least six months and correlate best with neutralisation independent of the presence and severity of COVID-19 symptoms. Research in contextO_ST_ABSEvidence before the studyC_ST_ABSAt the beginning of the study (early pandemic in April 2020), the SARS-Cov-2 specific seroprevalence was totally unknown. Additionally, S1-specific antibody assays being the first on the market were tested with limited sample size showing a lower sensitivity and specificity at that time. Furthermore, at that time, there were no unambiguous interpretations of antibody test results with regard to immunity/protection against reinfection. It was also not clear whether the detection of different antibody specificities could yield an essential input into the interpretation of the antibodys qualities. Another open question was how long antibodies of the various specificities as well as antibodies with protective capacities would persist. Added value of this studyWe provide data to confirm the most reliable correlation of RBD-specific antibodies with neutralising antibodies that are stable for at least six months. S1- and NCP-specific antibodies wane more quickly than RBD-specific antibodies, rendering them not as ideal candidates for longitudinal seroprevalence studies. Concerning symptoms, anosmia/dysgeusia was strongly associated with NT-seropositivity and seroprotection in the overall study population. Implications of all the available evidenceOur data suggest that RBD-specific total antibody measurements with assays of high specificity can be used for cross-sectional as well as longitudinal seroepidemiological studies, even in low-prevalence settings. Detection of these antibodies also indicates robust seroprotection for at least six months. Due to the substantial loss of S1- and NCP-specific antibodies within the first months, assays targeting these antigen specificities - in contrast to RBD-specific antibody measurements - are not optimal to assess the duration of seroprotection. Overall, respiratory symptoms alone were not useful in predicting a past infection with SARS-CoV-2. However, anosmia/dysgeusia appeared to be a significant diagnostic marker, in particular for mild COVID-19.
